Plug Issue
12-15-2007, 07:34 PM
#1
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Plug Issue I am currently using TR6 gapped to .025 and about 5000 rpms we are pretty sure the spark is getting blown out. AFR is good and no knock but when it hits 5000 rpms and 18psi boost it jerks like we are loosing spark. Anyone have any solutions? Should I gap closer?
Kane
Kane
12-15-2007, 09:38 PM
#6
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12-15-2007, 11:09 PM
#9
Your plugs aren't the problem--yet. Using a plug that is too hot will cause detonation later, but not spark blow-out. I'm guessing you have spring related valve control issues, ie "valve float". I'm betting some other problem would fubar your motor before you blow out the spark on a tr6 gapped at .025. With all of that being said, after you do find the real problem, the 6's may be too hot for 18psi.
12-16-2007, 12:04 AM
#11
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Forgot to add one thing when I take the car to the higher rpms not in boost everything is fine. So the issue starts at around 5000rpms if I run it up there with no boost the problem is not there.
Kane
Kane
12-16-2007, 01:53 AM
#12
Well without boost or not under a load isn't the same I am sure you know that though. I am with these guys there is another issue. What cam are you running? And Crane springs whats the numbers 832??? the added presure on the back side of the valve can effect it with a combination that is on the edge of being too much for the springs etc...
12-16-2007, 06:10 AM
#13
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On LS1's ?? or other motors ?
LS1's have very powerful coils, so there is no need to drop the gap down that small. The stock coils are well tried and tested, to crazy power levels. So unless you actually have some faulty coils....it is highly unlikely you do not have enough spark power.
LS1's have very powerful coils, so there is no need to drop the gap down that small. The stock coils are well tried and tested, to crazy power levels. So unless you actually have some faulty coils....it is highly unlikely you do not have enough spark power.
12-16-2007, 11:12 AM
#15
I run my TR6's or Autolite 103's with a .025 gap. I haven't had spark blow out issues until the boost reached 24psi (could have floated the valves too, I turned it back down after that).
Post the graph
Post the graph
Last edited by Zombie; 12-16-2007 at 11:19 AM.
12-16-2007, 12:58 PM
#17
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Let me give you guys some specs on the motor:
408
Custom JE Pistons
Eagle crank
Callies rods
Stock 6.0 heads
LS7 Cadillac lifters
Crane 832 dual springs
7400 pushrods
Yellow Terra Rockers
Now that the motor is broke in I may want to check the pushrod lengths again. At the time of the build the geometry was set.
Kane
408
Custom JE Pistons
Eagle crank
Callies rods
Stock 6.0 heads
LS7 Cadillac lifters
Crane 832 dual springs
7400 pushrods
Yellow Terra Rockers
Now that the motor is broke in I may want to check the pushrod lengths again. At the time of the build the geometry was set.
Kane
12-16-2007, 01:02 PM
#18
FormerVendor
First, you should check the ground strap of the plug immediately after a pull to determine heat range, which will likely be a 7 or 8 ngk at 18+psi boost. Also increase coil dwell time to 7ms by peak boost.
I do agree that it's likely insufficient valvesprings. Boost at the back of the intake valve is not a problem but backpressure on the back of the exhaust valve is. We usually try for a minimum 165psi seat pressure but sometimes go as high as 200psi on the seat in our higher horsepower hyd roller builds. We use stock rocker arms as well.
I do agree that it's likely insufficient valvesprings. Boost at the back of the intake valve is not a problem but backpressure on the back of the exhaust valve is. We usually try for a minimum 165psi seat pressure but sometimes go as high as 200psi on the seat in our higher horsepower hyd roller builds. We use stock rocker arms as well.
12-17-2007, 02:38 PM
#19
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So what is the easiest way to make totally sure it is actually valve springs? I had 918's in this car with the 408. We recently had to pull the motor and put new pistons in it because the clearences were to loose and it was causing piston slap in all cylinders. While the motor was out we upgraded to the Crane Duals and I put the LS7 lifter in. I did not have this issue with the Comp-R lifter and the 918 spring.
Here is a question we had a 7400 pushrod with a Comp-R lifter which is way to much preload. We now have a 7400 pushrod with LS7 lifters. The geometry was right at build time but may be off now. Will the valves float if the pushrods are to short?
I will get the covers off and do some testing to make sure everything is right up top.
Kane
Here is a question we had a 7400 pushrod with a Comp-R lifter which is way to much preload. We now have a 7400 pushrod with LS7 lifters. The geometry was right at build time but may be off now. Will the valves float if the pushrods are to short?
I will get the covers off and do some testing to make sure everything is right up top.
Kane
12-17-2007, 03:03 PM
#20
LS1Tech Co-Founder
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It's easy to swap in some NGK TR8's, I have them in both cars, and the Camaro runs just fine with them NA, though I put them in for the spray.
I ran Crane 832's a while back, they were okay but at one point I went to some Comps because it seemed like the Cranes were floating after I put in a more aggressive camshaft. I went from a 230/236 to a 236/246, maybe Jim remembers. I think we went to Comp 977's at that point, though I now run a set of ET springs with my AllPro heads.
I ran Crane 832's a while back, they were okay but at one point I went to some Comps because it seemed like the Cranes were floating after I put in a more aggressive camshaft. I went from a 230/236 to a 236/246, maybe Jim remembers. I think we went to Comp 977's at that point, though I now run a set of ET springs with my AllPro heads.
